The field of this invention relates to locking devices and more particularly to a key constructed of multiple parts for operating cylindrical, tubular types of locks, so that this type of key can be more easily and less expensively originated and duplicated.
The duplication of keys is normally a significant portion of business for every locksmith. At the present time, the normal method to duplicate any key requires the use of a key cutting machine. The key cutting machine is an expensive piece of equipment. Not only for well-established locksmiths but also for newly established locksmiths, such an expense can be prohibitive. Besides a straight type of key, there is also the tubular type of key. This means that a key cutting machine is not only required for the straight type of key, but also for the tubular type of key which constitutes a double machine expense.
Another disadvantage of requiring of a key cutting machine is that such machines are of substantial weight and size and not conducive to portability. Normally, portability is a requirement, since in most cases a locksmith is required to visit the site of a locksmithing situation. This means that the machine must be readily carried within a small truck or van. Still further, such machines require operation by electricity. At times, in certain situations, electricity may not be readily convenient.
Besides the aforementioned disadvantages in the duplicating of keys, there is also the disadvantage that the key that is duplicated is produced from another key. This other key is frequently worn through usage. Therefore, the wear of this master key is reproduced in the duplicate key. This amount of wear, coupled with a small amount of machine tolerance of the key cutting machine, frequently results in a key that will not work the lock for which it is intended. The duplicated key cannot be better than the key from which it was duplicated.
Previously, there has been an attempt by the present inventor to construct a key assembly which does not require the use of a key cutting machine to produce a duplicated key. This key assembly is defined within U.S. Pat. No. 4,045,983, issued Sept. 6, 1977, entitled "UNIVERSAL BARREL KEY APPARATUS". The subject matter of the present invention is an improvement over the structure of the aforementioned patent.